Nelson #1 Reservoir Report
Nearby: Anderson No.2 Anderson No.1
Last Updated: December 12, 2025
Nelson #1 is a privately owned dam located in Mellette, South Dakota, along the TR Oak Creek offstream.
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Summary
It was completed in 1950 and stands at a height of 28 feet with a length of 694 feet. The dam has a storage capacity of 64 acre-feet, with a normal storage level of 55 acre-feet. It is regulated by the South Dakota Department of Environment and Natural Resources (DENR) and is subject to state permitting, inspection, and enforcement.
Despite being classified as low hazard potential, the condition of Nelson #1 has not been rated. The dam has not been assessed for emergency action plans or risk management measures. It is not under the jurisdiction of the U.S. Army Corps of Engineers and does not have associated structures or locks. The maximum discharge capacity of the dam is 1075 cubic feet per second, indicating its importance in managing water flow in the area.
For water resource and climate enthusiasts, Nelson #1 presents an interesting case study of a privately owned dam in South Dakota. Its location along TR Oak Creek offstream highlights its significance in managing water resources in the region. The lack of condition assessment and emergency action planning raises questions about the potential risks associated with the dam and the need for proactive measures to ensure its safety and stability in the face of changing climate conditions.
Year Completed |
1950 |
Dam Length |
694 |
Dam Height |
28 |
River Or Stream |
TR OAK CREEK OFFSTREAM |
Primary Dam Type |
Earth |
Hydraulic Height |
28 |
Nid Storage |
64 |
Hazard Potential |
Low |
Nid Height |
28 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
White River Near White River
|
42cfs |
Little White R Below White River Sd
|
141cfs |
Keya Paha R Near Keyapaha Sd
|
33cfs |
Little White R Near Rosebud Sd
|
96cfs |
White R Near Oacoma Sd
|
105cfs |
Keya Paha R At Wewela Sd
|
54cfs |
Dam Data Reference
Condition Assessment
SatisfactoryNo existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.
Hazard Potential Classification
HighDams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.
Nelson #1